Mutant crystals in Na 2 O Æ 2CaO Æ 3SiO 2 glasses

This paper presents strong evidence for a continuous variation in glass and crystal compositions during crystallization, from the early stages of nucleation up to full transformation of a stoichiometric Na2O AE 2CaO AE 3SiO2 glass, as well as of similar glasses that are depleted or enriched in sodium. During crystallization, the crystal compositions approach those of the parent glasses, leading to the inference that the critical clusters were also sodium-enriched. The